The Ultimate checklist for drilling a borehole.
Having and drilling a borehole is an asset that should last you at least 10 to 15 years at very little ongoing cost, provided you do everything correctly at the start! If you don’t, it can become a very expensive and time-consuming liability with continual repair or replacement of pumps. The causes of which could either be traced back to poor borehole construction or incorrect pumping or pump installation.
The Borehole Water Association along with GEOSS has prepared a checklist to assist you when it comes to drilling a borehole. This includes your buying decision. One that should be based on ‘value’ and not on ‘price’ alone.
Location of Water:
- You should do some ‘homework’ to determine if there are boreholes in your neighbourhood. Do this by checking with your neighbours to see who has a borehole, if they have water, how much and how deep is it. Then you can work out (very basic information used only to back up professional opinion) what your chances of finding water are.
- Pinpoint the location for drilling the borehole. Get a geohydrologist to do this. Check on the past success rate of the person they usually use to ‘site’ their boreholes. In an urban environment, cultural interferences (powerlines, pipe lines, cables etc..) preclude the scientific siting of the borehole. In a limited space urban environment the borehole is often drilled where the rig can fit in (average water well rigs are + 15T & truck mounted.
- Check if the person you hired to site the borehole uses more than one method of cross checking.
Choice of Borehole Driller:
- Check references of previous clients who have had time to assess quality of work over a reasonable period of time.
- Check if he/she works to a recognized Standard. There are SABS Standards now available for the groundwater industry. SANS 10299-: 2003 – Development, Maintenance and Management of Groundwater Resources.
- Check what condition his/her equipment is in.
- Make sure his/her drill rods are straight.
- Check on type of casing/well screens to be used.
- Check on diameter of borehole to be drilled. A diameter of 152 mm (6 inches / 216 mm (8 inches), is recommended for a domestic borehole.
- Check if equipment can reach target depth.
- Check if he/she does borehole development and how he/she will improve water yield if necessary – if he/she does not understand the meaning of borehole development, get another driller.
- Check that you only have to pay him/her if he/she drills to depth specified (unless he/she finds water at a lesser depth).
- Check that he/she will be able to continue drilling when hitting intersecting clay, unconsolidated sand or hard rock.
- Check that he/she will provide samples of material of each and every metre drilled.
- Check before drilling whether there are any add-ons to be considered – such as a surcharge for abrasive lithologies or depths exceeding 100m.
- Check if he/she provides records of work carried out, e.g. driller’s log, construction certificate, electrical clearance, yield test certificate, pump details & commissioning data. When selling property, remember a borehole represents a substantial capital investment.
- Check that the driller provides a record of exact depth at which the most promising water fissure is located. This information is vital to the pump installer to enable him/her to select correct pump for your needs.
- Check if he/she has a standard form of contract. Of vital importance to both parties. The BWA has such a Contract to offer the end-user.
- Check if he/she is a member of the Borehole Water Association. Membership of the Association shows that the contractor/supplier you are dealing with is, interested in the long-term viability, professionalism and survival of the industry. It also gives you, the end user recourse should any problems arise during construction of your borehole.
Other factors that need to be taken heed of by you, the end user!!
- The drilling contractor can never guarantee that they will intersect water and therefore it is the client who is at risk for the cost of the borehole. This is regardless of whether it is wet or dry!
- A modern drilling rig is large & heavy – in urban areas it can cause a certain amount of unavoidable damage, and the contractor cannot reasonably be held responsible.
- Drilling rigs are noisy and they generally make a great deal of mess, both these factors are unavoidable. In urban areas neighbours should be warned that drilling will be taking place on your property.
- Under the New Water Law, your water usage may need to be registered with the Department of Water Affairs and Forestry – contact the ‘Acting Director of Water Resources Management’, at the Dept of water and Sanitation (DWS). Discuss with contractor as to who is responsible for making enquiry. Learn more about this here
- The local municipality/council may require that permission be obtained to sink a borehole. Discuss this with contractor, and find out who is responsible for making the enquiry.
- Ensure that there are no electrical cables, sewage or water pipes hidden under the ground where the drilling will take place.
- There are many unknowns, such as final depth, the amount required & time taken for development, so you need to agree on a suitable amount to be allowed for ‘add-ons’ with your contractor.
- Drillers levy a surcharge for drilling through very hard rocks, e.g. dolomite formation requires specialized expertise to drill into.
- Make sure that the driller caps the hole after drilling to prevent any foreign material entering the well. Best is if the borehole is welded closed.